Present day telecommunications networks typically include a plurality of switching systems linked via transmission facilities (e.g., trunks and/or channels) that carry "calls" (in the form of voice, video or data) between switching systems. Additionally, these switching systems are typically linked via a signaling (data) network that transmits signaling messages between switching systems. Further, within a given telecommunications network, control information may flow between switching systems and databases, intelligent peripherals, or other specialized resources, as is well known in the art.
A present day switching system includes a switching fabric and a control mechanism as a single integrated system. The control mechanism of a switching system provides the intelligence to operate a specific switching fabric and some (or possibly all) of the intelligence required to interpret and respond to signals. The switching fabric includes devices for the termination of transmission facilities, as well as devices that provide multiple stages of space and time switching as is understood in the art. Additionally, the switching fabric may also include local intelligence, in the form of a processor or the like, for acting upon commands from the control mechanism. Within prior art switching systems, the control mechanism includes one or more special purpose computers that control such functions as connecting communications paths, and to varying degrees, receiving and sending signaling messages, performing operations, administration and maintenance functions, and providing call processing and customer services (e.g., service logic).
The switching fabric of present day switching systems controls call routing. In other words, the switching fabric, under control of its associated intelligence, makes decisions regarding trunk selection in order to transmit calls to another fabric of another switching system. Various techniques presently exist for routing calls and will not be discussed in detail. Examples of call routing techniques include Real-Time Network Routing (RTNR), Success to the Top Routing (STT) as well as Class-Of-Service Routing.
The nature of the switching fabric in present day switching systems is dependent on the nature of the calls carried by that fabric. For example, circuit-switch type switching systems typically utilize one type of fabric for carrying voice calls. In contrast, Asynchronous Transfer Mode (ATM) switching systems typically utilize a packet-type fabric for carrying data calls. Different types of fabrics route calls differently. Even though two different types of fabrics may utilize a particular routing technique, the implementation of that technique within one type of fabric is often necessarily different from its implementation in another type of fabric. Thus, when implementing a new routing technique, different implementations must be provided for different types of fabrics. As a result, development costs for implementing a new routing technique tend to be expensive.
Thus, there is need for a technique for achieving fabric-independent routing.